1 files changed, 93 insertions, 0 deletions
diff --git a/core/src/main/java/org/elasticsearch/script/ScriptEngineRegistry.java b/core/src/main/java/org/elasticsearch/script/ScriptEngineRegistry.java
new file mode 100644
index 0000000000..4bc9a23eba
--- /dev/null
+++ b/core/src/main/java/org/elasticsearch/script/ScriptEngineRegistry.java
@@ -0,0 +1,93 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.script;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+
+public class ScriptEngineRegistry {
+
+    private final Map<Class<? extends ScriptEngineService>, List<String>> registeredScriptEngineServices;
+    private final Map<String, Class<? extends ScriptEngineService>> registeredLanguages;
+
+    public ScriptEngineRegistry(Iterable<ScriptEngineRegistration> registrations) {
+        Objects.requireNonNull(registrations);
+        Map<Class<? extends ScriptEngineService>, List<String>> registeredScriptEngineServices = new HashMap<>();
+        Map<String, Class<? extends ScriptEngineService>> registeredLanguages = new HashMap<>();
+        for (ScriptEngineRegistration registration : registrations) {
+            List<String> languages =
+                registeredScriptEngineServices.putIfAbsent(registration.getScriptEngineService(), Collections.unmodifiableList(registration.getScriptEngineLanguages()));
+            if (languages != null) {
+                throw new IllegalArgumentException("script engine service [" + registration.getScriptEngineService() + "] already registered for languages [" + String.join(",", languages) + "]");
+            }
+
+            for (String language : registration.getScriptEngineLanguages()) {
+                Class<? extends ScriptEngineService> scriptEngineServiceClazz =
+                    registeredLanguages.putIfAbsent(language, registration.getScriptEngineService());
+                if (scriptEngineServiceClazz != null) {
+                    throw new IllegalArgumentException("scripting language [" + language + "] already registered for script engine service [" + scriptEngineServiceClazz.getCanonicalName() + "]");
+                }
+            }
+        }
+
+        this.registeredScriptEngineServices = Collections.unmodifiableMap(registeredScriptEngineServices);
+        this.registeredLanguages = Collections.unmodifiableMap(registeredLanguages);
+    }
+
+    Iterable<Class<? extends ScriptEngineService>> getRegisteredScriptEngineServices() {
+        return registeredScriptEngineServices.keySet();
+    }
+
+    List<String> getLanguages(Class<? extends ScriptEngineService> scriptEngineService) {
+        Objects.requireNonNull(scriptEngineService);
+        return registeredScriptEngineServices.get(scriptEngineService);
+    }
+
+    Map<String, Class<? extends ScriptEngineService>> getRegisteredLanguages() {
+        return registeredLanguages;
+    }
+
+    public static class ScriptEngineRegistration {
+        private final Class<? extends ScriptEngineService> scriptEngineService;
+        private final List<String> scriptEngineLanguages;
+
+        public ScriptEngineRegistration(Class<? extends ScriptEngineService> scriptEngineService, List<String> scriptEngineLanguages) {
+            Objects.requireNonNull(scriptEngineService);
+            Objects.requireNonNull(scriptEngineLanguages);
+            if (scriptEngineLanguages.isEmpty()) {
+                throw new IllegalArgumentException("languages for script engine service [" + scriptEngineService.getCanonicalName() + "] should be non-empty");
+            }
+            this.scriptEngineService = scriptEngineService;
+            this.scriptEngineLanguages = scriptEngineLanguages;
+        }
+
+        Class<? extends ScriptEngineService> getScriptEngineService() {
+            return scriptEngineService;
+        }
+
+        List<String> getScriptEngineLanguages() {
+            return scriptEngineLanguages;
+        }
+    }
+
+}